1. Field of the Invention
This invention relates to a heat pump system usable as an air-conditioning apparatus, a refrigeration apparatus, or a temperature-conditioning apparatus, and in particular, to such an apparatus provided with an energy compensation system and/or a refrigerant flow control system which allow(s) for stable heat pumping operation by compensating for insufficient total heat-absorbing capacity, especially when condensation capacity increases due to, for example, a cold or windy environment. This invention also relates to a method for stable heat pumping operation.
2. Background of the Art
A heat pump system, which is used as an air-conditioning apparatus or a refrigeration apparatus, enables cooling the air in a room or a refrigerator by circulating refrigerant in a refrigerant circulation line through an outside heat-exchanger (condenser), an expansion valve, an inside heat-exchanger (evaporator), and an accumulator in sequence, with a compressor driven by an engine or an electric motor, for example.
In operating a heat pump system as an air-conditioning apparatus, for example, it is necessary in some cases to cool a room even when the outside is very cold or very windy because heat is internally generated in the room. When a heat pump system has an outside heat-exchanger with a heat exchange capacity sufficient for operating multiple inside heat-exchangers (evaporators), it is necessary in some cases to cool only some of the rooms, i.e., inside heat-exchangers.
In operating a heat pump system as a refrigeration apparatus, it is necessary in some cases to cool or freeze material in a storage compartment of a refrigerator such as a display case, which is placed in an air-conditioned (warm) room even when the outside is very cold or very windy. When a heat pump system has an outside heat-exchanger with a heat exchange capacity sufficient for operating an inside heat-exchanger (evaporator) with a high cooling capacity, it is necessary in some cases to operate the apparatus only with a low cooling capacity.
As understood from the above, when a heat pump system is used as an air-conditioning apparatus to cool the air in a room or as a refrigeration apparatus to cool the air in a storage compartment of a refrigeration apparatus, condensation capacity at an outside heat-exchanger (condenser) exceeds evaporation capacity at an inside heat-exchanger (evaporator) in some cases. When such cases occur, the pressure in a refrigerant circulation line upstream of an evaporation valve (i.e., on the high pressure side) decreases, the difference in pressure between upstream of and downstream of the evaporation valve, i.e., between the high pressure side and the low pressure side, is then reduced. As a result, the volume of a refrigerant passing through the evaporation valve is reduced, and then total heat-absorbing at the inside heat-exchanger (evaporator) is diminished, thereby lessening cooling capacity. Further, because the volume of refrigerant passing through the evaporation valve decreases, stable cooling and refrigeration operation suffers.